| IT Governance Consulting Limited | Information & communication | 2007 |
| IT Governance Europe Limited | Information & communication | 2016 |
| IT Governance Franchising Limited | Information & communication | 2007 |
| IT Governance Limited | Information & communication | 2002 |
| IT Governance Publishing Ltd | Information & communication | 2007 |
| IT Governance Sales Ltd | Information & communication | 2008 |
| IT Governance Software Ltd | Extraterritorial | 2007 |
| IT Governance Training Limited | Information & communication | 2007 |
| IT Improve Ltd. | Information & communication | 2015 |
| IT Kitt Ltd | Information & communication | 2011 |
| Italian Jewellery Limited | Wholesale & retail | 2005 |
| Itech ELY Ltd | Wholesale & retail | 2024 |
| ITG Certification Limited | Extraterritorial | 2010 |
| ITG Encryption Limited | Information & communication | 2018 |
| ITG Qualifications Ltd | Education | 2013 |
| ITG Security Testing Ltd | Extraterritorial | 2009 |
| ITS Wonderful Limited | Wholesale & retail | 2014 |
| Iulian Mihai Limited | Transport & logistics | 2018 |
| Ivor Searle Limited | Manufacturing | 1978 |
| Ivory Management Services Ltd | Professional & scientific | 2025 |
| IVY Bone Bridal Ltd | Wholesale & retail | 2025 |
| Izzard and Russell Investments Ltd | Real estate | 2000 |
| J & J a Construction Limited | Construction | 2003 |
| J & R Developments (Cambridge) Limited | Construction | 2014 |
| J & S Nails Soham Ltd | Other services | 2025 |
| J & V Gaskin Limited | Construction | 2018 |
| J Collection Ltd | Manufacturing | 2021 |
| J D Glass Limited | Construction | 2007 |
| J Doyle Building Contractors Limited | Construction | 2014 |
| J G Carpentry and Joinery Limited | Construction | 2014 |
| J Harvey Ltd | Real estate | 2010 |
| J L Aspden Limited | Information & communication | 1998 |
| J Leigh Inspection Services Ltd | Professional & scientific | 2024 |
| J M R Property Sourcing Ltd | Real estate | 2018 |
| J Q Family Holdings Limited | Administrative & support | 2026 |
| J Shepherd Engineering Limited | Transport & logistics | 2014 |
| J Townson Consulting Ltd | Information & communication | 2022 |
| J Withell Joinery Limited | Manufacturing | 2014 |
| J&E Clothing Alterations and Repairs Ltd | Other services | 2015 |
| J&M Brickwork Ltd | Construction | 2013 |
| J. & J.A. Borland Ltd. | Construction | 2001 |
| J. M. Ward Building Ltd | Construction | 2019 |
| J.A.Taylor (Fordham) Limited | Agriculture & fishing | 1962 |
| J.B Shropshire & Sons Limited | Agriculture & fishing | 1998 |
| J.C.Beasley Plumbing and Heating Ltd | Construction | 2013 |
| J.K. Interior Fitters Ltd | Construction | 2025 |
| J2B Logistics Ltd | Transport & logistics | 2024 |
| Jackson Immunoresearch Europe Limited | Wholesale & retail | 2004 |
| Jalsea Marine Services Limited | Administrative & support | 1997 |
| James Armer Consulting Ltd | Information & communication | 2023 |
| James Loosley Electrical Limited | Construction | 2016 |
| James of ELY Limited | Wholesale & retail | 2014 |
| Jamie LE Brun Golf Ltd | Wholesale & retail | 2026 |
| JAN Vincent Limited | Administrative & support | 2010 |
| Janette Murphy Dental Hygiene Services Limited | Health & social care | 2012 |
| Jans Coaches Ltd | Transport & logistics | 2012 |
| Jask Consultants Limited | Information & communication | 2000 |
| Jason Webb Plumbing & Heating Ltd | Construction | 2011 |
| Jaxdene Recruitment Ltd | Administrative & support | 2024 |
| Jaxdene Trading Ltd | Transport & logistics | 2019 |
| Jazzyfaction Ltd | Arts & recreation | 2023 |
| JB & PS Farms Holdings Limited | Financial services | 2022 |
| Jb's Hair Salon Limited | Other services | 2013 |
| Jbdt Limited | Hospitality | 2019 |
| JBH Interactive Ltd | Information & communication | 2015 |
| JBL Bricklaying & Building Services Limited | Construction | 2006 |
| JC Links Solutions Ltd | Information & communication | 2025 |
| JC Trading Services Ltd | Wholesale & retail | 2024 |
| Jcstech Ltd | Professional & scientific | 2024 |
| JD Garden & Landscaping Ltd | Other services | 2017 |
| Jeae Ltd | Real estate | 2026 |
| Jellyfish Comics UK Ltd | Manufacturing | 2026 |
| JEM International Limited | Wholesale & retail | 2004 |
| Jens 2020 Ltd | Financial services | 2020 |
| JEX Waste Management Ltd | Water & waste | 2023 |
| Jezo's Events Ltd | Arts & recreation | 2015 |
| Jgpoole&Co LLP | | 2013 |
| JHA Vision Limited | Administrative & support | 2018 |
| Jiggerme Ltd | Real estate | 2020 |
| Jipd Limited | Real estate | 2016 |
| JJ Luxury Autos Ltd | Wholesale & retail | 2021 |
| JJM Landscapes Limited | Administrative & support | 2019 |
| JJP & Associates Ltd | Professional & scientific | 2019 |
| Jkpm Limited | Construction | 2023 |
| JM New Idea Ltd | Construction | 2015 |
| JM Software Solutions Limited | Information & communication | 2012 |
| JMB Aviation Services Limited | Administrative & support | 2017 |
| JMB Lighting Ltd | Construction | 2021 |
| JMB Suppliers Ltd | Wholesale & retail | 2022 |
| JMF Building Services (Soham) Limited | Construction | 2012 |
| JMH Engineering Ltd | Manufacturing | 2015 |
| JMU Child and Family Service Ltd | Health & social care | 2024 |
| JNU Carpentry Ltd | Extraterritorial | 2022 |
| JOB Link (Soham) Ltd | Professional & scientific | 2005 |
| JOE Ison Health and Fitness Limited | Other services | 2025 |
| JOE Perry's Snooker & Pool Palace Limited | Arts & recreation | 2023 |
| John Audus (Electrical Contractors) Limited | Construction | 2002 |
| John Hazle Wealth Management Ltd | Professional & scientific | 2020 |
| John LEE (Potatoes) Limited | Wholesale & retail | 1993 |
| John Watts Editor Ltd. | Information & communication | 2015 |